The present invention relates to the acquisition and ascertainment of dimensions and measurements of an object under utilization of photographic method, and more particularly the invention relates to photographically acquired dimensions and measurements of the contour (topography) of a human body.
Topographic method and equipment is known wherein a photographic image of an object that is the subject of measurement and dimensions acquisition, is taken together with a measuring raster in superimposed relationship e.g. as double exposure; and during the taking of the picture horizontal lines are projected onto the object. The reflection of these lines will be distorted of deflected up or down by any unevennesses of the surface of the object. These distortions in relation to the measuring raster give then a measurement of the third dimension.
A method and equipment of this kind is for example shown in U.S. Pat. No. 4,370,039 corresponding to German patent No. 29 48 010 and U.S. Pat. No. 4,639,107 corresponding to German patent No. 34 25 913. Both references show a projection of the horizont lines from above and oblique as far as the object plane of the object is concerned in order to make visible the three dimensions by up or down deflection of the horizontal raster lines. The drawings in the first mentioned patent indicate particularly this capability. For example if a horizontal line is deflected up the local topography of the object is closer to the camera i.e. it indicates a bulging stomach or in case of a down deflection the indication is that of an indent. The measuring raster which is superimposed in the form of a double exposure then in relation to the visible and deflected projection lines permits an accurate measurement concerning all three dimensions.
The line pattern is projected through a slide and flash light projector. This particular method is highly practical and has however the disadvantage that in the case of a tall person it may be necessary to consider the fact that the angle of projecting the line pattern is variable one. Usually it is practical to have the center axis at an orientation of 45 degrees to the vertical but there are then considerable parts of the projection which impinge upon the body at a larger angle such as the head area while the legs receive projection of line pattern that is much shallower angle less than 45 degrees. This in turn requires establishing a recalibration and to provide a relatively complicated algorithm in order to offset this variation. While possible in principle it was found that the digitalization is really a significant problem.
In order to offset this draw U.S. Pat. No. 4,786,925 corresponding to German patent No. 36 21 927 proposes a plurality of such projectors all with projections axes that run in parallel and all e.g. 45 degrees to the vertical. Deviations from the average angle are in fact very small and introduce a negligible error only. The projection as a whole and then the reflection of the projected lines do indeed present a very accurate topographic picture of the body. Unfortunately the equipment cost for this procedure is very high and there is definitely a need for simplification in terms of economy.